MUCH OF THE INCREASED RISK OF DEATH FROM SMOKING REDUCED
WITHIN SEVERAL YEARS AFTER QUITTING
CHICAGO—Women who quit smoking significantly reduce their
risk of death from coronary heart disease within 5 years and
have about a 20 percent lower risk of death from smoking-related
cancers within that time period, according to a study in the May
7 issue of JAMA.
“Tobacco use remains the leading preventable cause of death in
the United States. Globally, approximately 5 million premature
deaths were attributable to smoking in 2000. The World Health
Organization projects by 2030 that tobacco-attributable deaths
will annually account for 3 million deaths in industrialized
countries and 7 million in developing countries,” the authors
write. They add that the rate of mortality risk reduction after
quitting compared with continuing to smoke is uncertain.
Stacey A. Kenfield, Sc.D., of the Harvard School of Public
Health, Boston, and colleagues assessed the relationship between
cigarette smoking and smoking cessation on total and
cause-specific mortality in women by analyzing data from the
Nurses’ Health Study, an observational study of 104,519 female
participants, with follow-up from 1980 to 2004. A total of
12,483 deaths occurred in this group, 4,485 (35.9 percent) among
never smokers, 3,602 (28.9 percent) among current smokers, and
4,396 (35.2 percent) among past smokers.
The researchers found a significant 13 percent reduction in the
risk of all-cause mortality within the first 5 years of quitting
smoking compared with continuing to smoke, and the excess risk
decreased to the level of a never smoker 20 years after
quitting, with some causes taking more or less time.
“Significant trends were observed with increasing years since
quitting for all major cause-specific outcomes. A more rapid
decline in risk after quitting smoking compared with continuing
to smoke was observed in the first 5 years for vascular diseases
compared with other causes.”
“Much of the reduction in the excess risk for these causes of
death were realized within the first 5 years for coronary heart
disease and cerebrovascular disease. Sixty-one percent of the
full potential benefit of quitting in regard to coronary heart
disease mortality and 42 percent of the full potential benefit
of quitting in regard to cerebrovascular mortality was realized
within the first 5 years of quitting smoking, when comparing
hazard ratios for recent quitters of less than 5 years with
long-term quitters of 20 years or greater. For death due to
respiratory disease, an 18 percent reduction in risk of death
was observed 5 to 10 years after quitting smoking, with the risk
reaching that of a never smoker’s risk after 20 years.”
For lung cancer mortality, a significant 21 percent reduction in
risk was observed within the first 5 years compared with
continuing smokers, but the excess risk did not disappear for 30
years. Past smokers with 20 to less than 30 years of cessation
had an 87 percent reduction in risk of lung cancer mortality
compared with current smokers. When including the other
smoking-related cancers, the excess risk approached a never
smoker’s risk more than 20 years after quitting smoking.
Significant trends were observed for earlier age at initiation
of smoking for total mortality, respiratory disease mortality,
and all smoking-related cancer mortality. The data also
suggested that smoking is associated with an increased risk of
colorectal cancer mortality but not ovarian cancer mortality.
The researchers also found that approximately 64 percent of
deaths among current smokers and 28 percent of deaths among
former smokers were attributable to cigarette smoking.
“Early age at initiation is associated with an increased
mortality risk so implementing and maintaining school tobacco
prevention programs, in addition to enforcing youth access laws,
are key preventive strategies. Effectively communicating risks
to smokers and helping them quit successfully should be an
integral part of public health programs,” the authors conclude.
(JAMA. 2008;299[17]:2037-2047. Available pre-embargo to the
media at www.jamamedia.org)
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